As already stated in Applicant's Canadian patent No. 1,223,441 (issued on Jun. 30, 1987), sign boards are used in public places, such as stores, banks and the like, to display advertizing and messages, the elements of which must be changed from time to time, for instance the price of certain items to be sold or the interest rate available in a bank.
Even though Applicant's Canadian patent No. 1,223,441 solved several problems that were encountered with former sign boards, namely the use of display elements that were either complex and expensive to manufacture or did not obey with fundamental rules for graphic arrangement of said display elements, some problems were left unsolved. Amongst these unsolved problems, it may be cited the followings:
When a sign board, for example a sign board of the type described in Canadian patent No. 1,223,441, U.S. Pat. No. 3,148,469 or German patent No. 843,498 is accidentally dropped on a floor (especially when display sheets are changed (i.e. the optional locking strip of Canadian patent No. 1,223,441 or the top wall of U.S. Pat. No. 3,148,469 being removed)), stacks of display sheets may slip out from their corresponding pockets and become mixed together or some display sheets may be lost. Such an accident may make the sign board expensive to use because an employee has to spend time to reform stacks of display sheets, or may become useless because some display sheets are lost.
In sign boards of the prior art, such as the sign boards of Canadian patent No. 1,223,441, U.S. Pat. No. 3,148,469 or German patent No. 843,498, pockets in which stacks of display sheets are housed, are in a fixed relationship one with respect to the other. Therefore, they cannot be moved one with respect to the other when it is required to center an advertising or a message in order to meet with fundamental rules for graphic arrangement.
In sign boards of the prior art, means may be provided in order to keep them into a substantially vertical position. For example, in U.S. Pat. No. 3,148,469, projecting edges and springy wire elements of a display device may be engaged between a pair of opposite grooves of a metal molding strip that is secured on the front edge of a shelf. Also, in German patent No. 843,498, needles may be secured on a box. However, none of prior art sign boards were provided with means allowing to easily and removably connect them with a base adapted to rest on a substantially horizontal surface or element, in order to keep said sign boards into a substantially vertical position.